On Succession in A Saxicolous Lichen Community

1985 ◽  
Vol 17 (2) ◽  
pp. 167-172 ◽  
Author(s):  
M. E. J. Woolhouse ◽  
R. Harmsen ◽  
L. Fahrig
Keyword(s):  
Community Diversity ◽  
Rock Surface ◽  
Surface Erosion ◽  
Physical Weathering ◽  
Rock Face ◽  
Lichen Community ◽  
Competition For Space ◽  
Allogenic Processes ◽  
Opening Up ◽  
Lichen Flora

AbstractThe lichen flora was sampled at each of the five sites on a near-vertical gneiss rock face. The sites were ranked according to the degree ofweathering of the rock surface and were taken to represent different stages in a succession. The succession shows an increase in species richness and diversity over time, although the proportion of the rock face unoccupied by lichens increases at the oldest site. The succession will be driven by allogenic processes, physical weathering of the rock, facilitation, especially the effects of lichens on surface erosion, and by inhibition, through competition for space. At the oldest site mortality of lichen thalli becomes important, continually opening up new areas for recolonization and maintaining community diversity. The succession may be described by four phases: (1) colonization, (2) growth,(3) competition and (4) senescence.

scholarly journals Spatial Distribution of Lichens in Metrosideros excelsa in Northern New Zealand Urban Forests

Diversity ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 170
Author(s):  
Gladys N. Benitez ◽  
Glenn D. Aguilar ◽  
Dan Blanchon
Keyword(s):  
Spatial Distribution ◽  
Species Richness ◽  
New Zealand ◽  
Lichen Species ◽  
Positive Correlation ◽  
Breast Height ◽  
Lichen Community ◽  
The North ◽  
The City ◽  
Lichen Flora

The spatial distribution of corticolous lichens on the iconic New Zealand pōhutukawa (Metrosideros excelsa) tree was investigated from a survey of urban parks and forests across the city of Auckland in the North Island of New Zealand. Lichens were identified from ten randomly selected trees at 20 sampling sites, with 10 sites classified as coastal and another 10 as inland sites. Lichen data were correlated with distance from sea, distance from major roads, distance from native forests, mean tree DBH (diameter at breast height) and the seven-year average of measured NO2 over the area. A total of 33 lichen species were found with coastal sites harboring significantly higher average lichen species per tree as well as higher site species richness. We found mild hotspots in two sites for average lichen species per tree and another two separate sites for species richness, with all hotspots at the coast. A positive correlation between lichen species richness and DBH was found. Sites in coastal locations were more similar to each other in terms of lichen community composition than they were to adjacent inland sites and some species were only found at coastal sites. The average number of lichen species per tree was negatively correlated with distance from the coast, suggesting that the characteristic lichen flora found on pōhutukawa may be reliant on coastal microclimates. There were no correlations with distance from major roads, and a slight positive correlation between NO2 levels and average lichen species per tree.

The role of freezing-thaw cycling in rock samples topography evolution and rock cliff retreat

2021 ◽  
Author(s):  
Li Fei ◽  
Marc-Henri Derron ◽  
Tiggi Choanji ◽  
Michel Jaboyedoff ◽  
Chunwei Sun ◽  
...  
Keyword(s):  
Freezing Point ◽  
Meteorological Data ◽  
Test Chamber ◽  
Monitoring Program ◽  
Dynamic Environment ◽  
Rock Properties ◽  
Rock Surface ◽  
Physical Weathering ◽  
Rock Samples

<p>Freezing-thaw weathering is recognized as one of the most significant factors in the fatigue of rock mass in areas where the temperature periodically fluctuates around the freezing point. <br>A one-year monthly SfM monitoring program from December 19, 2019, to January 7, 2021, was done to detect rockfall activity on a rockslide cliff composed of marl-sandstone at La Cornalle, Switzerland. More than one hundred rockfall events were detected during this period with the volumes varied from 0.005m<sup>3</sup> to 4.85m<sup>3</sup>. <br>We texture all the rockfalls on the 3D SfM model. It is shown that most of them are mainly located in three areas:  the top of the cliff, the foot of the cliff, and the medium-left part of the cliff. The common feature of these three parts is that the layers are more or less overhanging with dense fractures around them. At the same time, the meteorological data collected by a weather station on site is correlated with the rockfall events to figure out the relationship between each other. Actually, about 30% of total rockfall volume fell during winter on this site. The triggering factor of rockfall during winter is related to freezing-thaw cycling. This kind of weathering can be understood as an interplay between rock properties and its dynamic environment.<br>In order to make clear the role of freezing-thaw played on the rockfall generation, an on-site 24h monitoring measurement program that consists of two crack meters, one rock thermal sensor, and thermal camera monitoring is installed in January 2021. Those datasets will help to understand how the crack grows with the changing temperature. In addition, freezing-thaw cycling laboratory experiments for the rock samples taken from different areas of the cliff will be done with an environmental test chamber. The topography of the rock samples before and after the experiments will be acquired by a 3D handheld scanner. This work will benefit to reveal the rock surface evolution during the freezing-thaw cycling in a dynamic environment with varied humidity and number of cycles. <br>In conclusion, the combination of on-site measurements and laboratory freezing-thaw experiments will provide a good basis for a better understanding of the rockfall triggering mechanism led by physical weathering.</p>

scholarly journals Temporal-Spatial Frequency Rockfall Data from Open-Pit Highwalls Using a Low-Cost Monitoring System

2020 ◽  
Vol 12 (15) ◽  
pp. 2459
Author(s):  
Anna Giacomini ◽  
Klaus Thoeni ◽  
Marina Santise ◽  
Fabrizio Diotri ◽  
Shaun Booth ◽  
...  
Keyword(s):  
Monitoring System ◽  
Low Cost ◽  
Surface Mining ◽  
Open Pit ◽  
Rock Surface ◽  
Accurate Information ◽  
Stereo Pair ◽  
Mining Operations ◽  
Rockfall Hazard ◽  
Rock Face

In surface mining, rockfall can seriously threaten the safety of personnel located at the base of highwalls and cause serious damage to equipment and machinery. Close-range photogrammetry for the continuous monitoring of rock surfaces represents a valid tool to efficiently assess the potential rockfall hazard and estimate the risk in the affected areas. This work presents an autonomous terrestrial stereo-pair photogrammetric monitoring system developed to observe volumes falling from sub-vertical rock faces located in surface mining environments. The system has the versatility for rapid installation and quick relocation in areas often constrained by accessibility and safety issues and it has the robustness to tolerate the rough environmental conditions typical of mining operations. It allows the collection of synchronised images at different periods with high-sensitivity digital single-lens reflex cameras, producing accurate digital surface models (DSM) of the rock face. Comparisons between successive DSMs can detect detachments and surface movements during defined observation periods. Detailed analysis of the changes in the rock surface, volumes and frequency of the rocks dislodging from the sub-vertical rock surfaces can provide accurate information on event magnitude and return period at very reasonable cost and, therefore, can generate the necessary data for a detailed inventory of the rockfall spatial-temporal occurrence and magnitude. The system was first validated in a trial site, and then applied on a mine site located in NSW (Australia). Results were analysed in terms of multi-temporal data acquired over a period of seven weeks. The excellent detail of the data allowed trends in rockfall event to be correlated to lithology and rainfall events, demonstrating the capability of the system to generate useful data that would otherwise require extended periods of direct observation.

scholarly journals Lichen community diversity on a remnant forest in south of Chaco region (Cordoba, Argentina)

2014 ◽  
Vol 35 (1) ◽  
pp. 9-10 ◽  
Author(s):  
Cecilia Estrabou ◽  
Carolina Quiroga ◽  
Juan Manuel Rodríguez
Keyword(s):  
Community Diversity ◽  
Lichen Community ◽  
Chaco Region ◽  
Remnant Forest

The effect of weathering on rock wall erosion and rockfall generation at La Cornalle, Switzerland

2020 ◽  
Author(s):  
Li Fei ◽  
Marc-Henri Derron ◽  
Tiggi Choanji ◽  
Michel Jaboyedoff ◽  
Chunwei Sun
Keyword(s):  
Rock Mass ◽  
Monitoring Program ◽  
Time Lapse ◽  
Effect Of Temperature ◽  
Rock Surface ◽  
Rock Wall ◽  
Rock Face ◽  
Surface Areas ◽  
Thaw Cycle ◽  
Rock Temperature

<p>The weathering posing a significant influence on the rock wall retreat has been widely recognized. In this paper, multi-methods monitoring is designed to detect the erosion and rockfall activity on a rockslide cliff composed of marl-sandstone (maybe mixed with limestone) in Western Switzerland. The monitoring program includes weekly SfM and monthly LiDAR scanning measurements of rock cliff surface, hourly time-lapse imaging of the rock cliff, manual measurement of rock surface moisture, automated recordings of rock temperature and influencing meteorological factors (air temperature, humidity, wind, and precipitation) collected by a weather station. Sequential 3D Points Clouds acquired by LiDAR and SfM from December 2019 are used to visually identify the location of erosion and rockfall at monthly resolution. According to the rock wall structural analysis, the rock mass consists of a network of discontinuities mainly oriented nearly parallel and perpendicular to the direction of the layers. Some fractures are filled with calcite which might lead to a zone of weakness in the rock mass. During the field survey, we saw some calcite crystals covering on the rock block surface in the deposit area and exposed on rock cliff outcrop. We suppose that some rockfalls are generated along those discontinuities filled with calcite where the chemical reaction is active when there is constant water infiltrating during rainfall season. According to the preliminary panoramic thermal image of the cliff surface shot by DJI Mavic 2 Enterprise on 19 December 2019, some weathered and fresh surface areas show different temperatures in the same rock layers which suggest the thermal imaging monitoring may help us to identify the weathering spatial characteristics. In this study, we try first to reveal the effect of temperature variations (thermal stress) on crack deformation from rock temperature values extracted from thermal images and the deformation measured by the crack meter during 24h in winter and summer. Secondly, we explore the role of freeze-thaw cycle playing in the rock fall initiation and rock face erosion. Thirdly, we make clear the link between surface weathering spatial distribution and location of erosion, rockfalls. This provides a model of weathering and rockfall estimation.</p>

Notes and Inscriptions from Pisidia. Part II

1960 ◽  
Vol 10 ◽  
pp. 43-82 ◽  
Author(s):  
G. E. Bean
Keyword(s):  
The Other ◽  
Rock Surface ◽  
Mountain Range ◽  
The South ◽  
The West ◽  
Main Road ◽  
Rock Face ◽  
Eastern Side ◽  
East And West ◽  
The Hill

I pass now to the eastern side of the central mountain range, to the ancient sites lying east and west of the main Burdur–Antalya road.In the little plain of Çineovası, 13 km. from Burdur, about 300 yards east of the main road, just opposite the 110th kilometre-stone from Antalya, is a rocky hill some 40 m. high carrying a small fortified site that seems hitherto to have escaped observation. The top of the hill has been levelled to form an area some 25 by 15 m., surrounded on all four sides by a wall of excellent coursed polygonal masonry 1·20 m. thick (Pl. Va). On the west this wall merely supplements the precipitous rock-face; on the other sides it still stands to a height of some 5 m., and was originally much higher, as beds for polygonal blocks can be seen in several places in the rock-surface on the summit, and great quantities of these blocks are lying on the slopes below. In the interior are traces of four or five walls up to 1 m. thick, now flush with the ground, and a large rock-cut cistern some 5 by 4 m. and over 2 m. deep. At the south-east corner are the collapsed ruins of an ornamented building, the blocks carefully cut, with mouldings and clamp-holes; one of these blocks forms a shallow anta. Two architectural blocks apparently belonging to this building are lying in the cistern.

scholarly journals Investigation of the importance of rock chemistry for saxicolous lichen communities of the New Idria serpentinite mass, San Benito County, California, USA

2012 ◽  
Vol 44 (5) ◽  
pp. 695-714 ◽  
Author(s):  
Nishanta RAJAKARUNA ◽  
Kerry KNUDSEN ◽  
Alan M. FRYDAY ◽  
Ryan E. O'DELL ◽  
Nathaniel POPE ◽  
...  
Keyword(s):  
Alpha Diversity ◽  
Fluorescence Analysis ◽  
Major And Trace Elements ◽  
Ultramafic Rocks ◽  
Generic Level ◽  
Central California ◽  
X Ray ◽  
Lichen Community ◽  
Serpentinized Peridotite ◽  
Lichen Flora

AbstractAlthough several lichen inventories exist for European ultramafic sites, only four surveys of serpentine lichens for North America have been published to date. Of those, only one has been conducted in California. We conducted a survey of saxicolous lichens from ultramafic rocks (including nephrite, partially serpentinized peridotite, and serpentinite) and non-ultramafic rocks (including silica-carbonate, shale, and sandstone) at the New Idria serpentinite mass, San Benito County, California. X-ray Fluorescence Analysis of the rocks from which the lichens were collected revealed significant elemental differences between the ultramafic and non-ultramafic rocks for 26 of the 32 major and trace elements analyzed. We identified a total of 119 species of lichenized and lichenicolous fungi; 60 species were restricted to ultramafic substrata, 19 to silica-carbonate, and 15 to shale and sandstone. Only 4 species were shared in common. A permutational multivariate analysis of variance (perMANOVA) test revealed significant differences in lichen assemblages between ultramafic and non-ultramafic rocks at the species level but not at the generic level, with species richness (alpha-diversity) significantly greater at the ultramafic sites. We suggest that, although differences in geochemistry clearly influence the lichen community composition, other factors, especially substratum age and the physical characteristics of the rock, are of equal, if not greater, importance. Of all the species collected, six, Buellia aethalea, B. ocellata, Caloplaca oblongula, Rhizocarpon saurinum, Thelocarpon laureri, and Trapelia obtegens, are reported new to California, along with an apparently previously undescribed Solenopsora sp. The rest of the species encountered are relatively frequent in the lichen flora of southern and central California, except Aspicilia praecrenata, a rare California endemic that we collected on both ultramafic and non-ultramafic rocks.

Escaping predators on vertical surfaces: Lacerta perspicillata in limestone quarries of Lithaca

2002 ◽  
Vol 80 (10) ◽  
pp. 1803-1809 ◽  
Author(s):  
Laurie J Vitt ◽  
William E Cooper, Jr. ◽  
Anna Perera ◽  
Valentín Pérez-Mellado
Keyword(s):  
Escape Behavior ◽  
Balearic Islands ◽  
Rock Surface ◽  
Limestone Quarry ◽  
Rock Face ◽  
Escape Strategy ◽  
Avian Predators ◽  
Straight Line ◽  
Escape Responses ◽  
Limestone Quarries

Escape behavior of the Mediterranean lizard Lacerta perspicillata was studied experimentally in a limestone quarry at Lithica on the island of Menorca, Balearic Islands, Spain. These lizards are exposed to avian predators while active on vertical rock faces. Simulated kestrel attacks using a cardboard model elicited escape responses from nearly all lizards approached. Methods of escape included entering a crevice, retreating over or around an edge, running behind a shrub growing against the rock surface, running behind a shrub and dropping to the ground ("bush to ground"), and retreating under or behind a rock isolated from a rock face. Most lizards fled directly to the closest available refuge or to alternative refuges only slightly farther away. Nevertheless, lizards that initially perched near crevices more frequently fled to other types of refuge than lizards that were initially near other refuges. The latter usually fled to the closest refuge. Lizards predominantly fled parallel to the ground or directly toward it (down) into a refuge regardless of the direction of attack (above, below, straight on). Direction of attack affected the type of refuge used. Lizards approached from above were more likely to flee to bush-ground or crevices than those approached from below or the same height. Straight-line retreat directly to a refuge appears to be the most viable escape strategy for these lizards when faced with attacks by avian predators, but the direction of attack may influence decisions based on risk.

Soil–landscape response to mid and late Quaternary climate fluctuations based on numerical simulations

2013 ◽  
Vol 79 (3) ◽  
pp. 452-457 ◽  
Author(s):  
Sagy Cohen ◽  
Garry Willgoose ◽  
Greg Hancock
Keyword(s):  
Climate Change ◽  
Late Quaternary ◽  
System Modeling ◽  
Surface Erosion ◽  
Climatic Fluctuations ◽  
Modeling And Analysis ◽  
Physical Weathering ◽  
Quaternary Climate ◽  
Soil Landscape ◽  
Landscape Response

AbstractWe use a numerical dynamic soil–landscape model to study one aspect of the spatio-temporal soil–landscape evolution process, the effect of climatic fluctuations on soil grading distribution in space and time in response to the interplay between physical weathering and surface erosion (soil mineralogical fluxes). We simulate a synthetic soil–landscape system over the middle and late Quaternary (last 400 ka). The results show that (1) soil–landscape response to climate change is non-linear and highly spatially variable, even at hillslope scale; and (2) soil–landscape adjustment to climate change can lag tens of thousands of years and is both spatially and temporally variable. We propose that the legacy of past climatic condition (i.e. last glacial maximum) in modern soil–landscape systems vary considerably in space. This implies that the spatiotemporal uniformity in which soil is typically described in Earth system modeling and analysis (e.g. carbon cycle) grossly underestimates their actual complexity.

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